In one conventional data storage arrangement, a computer node includes a host processor and a host bus adapter (HBA). The HBA is coupled to a data storage device. A host processor in the computer node issues a first data transfer request that complies with a first protocol. The HBA converts the request into one or more other data transfer requests that comply with a second protocol, and issues the one or more other requests to the data storage device. In this arrangement, it is possible that the data transfer amount requested by a single data transfer request according to the first protocol may exceed the maximum data transfer amount that a single data transfer request according to the second protocol can request.
One proposed solution to the problem is to restrict the maximum data transfer amount that can be requested by a single data transfer request according to the first protocol such that it is less than or equal to the maximum data transfer amount that can be requested by a single data transfer request according to the second protocol. Disadvantageously, one or more processes that implement the first protocol are modified to carry out this proposed solution; this may limit the types of processes that may be executed to implement the first protocol. Also disadvantageously, a greater number of data transfer requests according to the first protocol may be generated and issued; this may increase the amount of processing resources that may be consumed to generate data transfer requests according to the first protocol.
In another proposed solution, if the data transfer amount requested by a data transfer request according to the first protocol exceeds the maximum data transfer amount that can be requested by a single data transfer request according to the second protocol, the HBA generates and stores in memory a linked list of separate data transfer requests according to the second protocol. The respective data transfer amounts requested by the separate requests sum to the data transfer amount requested by the data transfer request according to the first protocol. Disadvantageously, implementation of this proposed solution consumes an undesirably large amount of memory. Also disadvantageously, this proposed solution fails to appreciate possible data proximity in cache memory; this may result in inefficient use of cache memory.
Although the following Detailed Description will proceed with reference being made to illustrative embodiments of the claimed subject matter, many alternatives, modifications, and variations thereof will be apparent to those skilled in the art. Accordingly, it is intended that the claimed subject matter be viewed broadly, and be defined only as set forth in the accompanying claims.